Councils monitor lakes' blue-green algae levels

The Ararat and Corangamite councils are watching for changes in lakes found to have toxic levels of blue-green algae.

Warning signs have been put up around Alexander Lake and Cobden Lake, after they were found to have excessive levels of toxins in the water.

The Corangamite Shire Council's Lyall Bond says the warmer weather can boost the presence of algae.

He says it is important for people to avoid algal blooms for health reasons and check the water quality before entering.

"We tend to see at Cobden Lake at the moment is that the water colour, it's actually quite a bright green," he said.

"Sometimes what you'll see in lakes, particularly if it's windy, you'll see on the edge of the lake on the windward side, that there's actually a thick scum and it's green but then you'll see like a light blue, I suppose you'd call it almost [a] paint-like substance."